1. Technical Field
The present application relates to surgical clip appliers, and in particular relates to instruments having a plurality of clips for applying the clips to body tissues and vessels during surgical procedures.
2. Discussion of the Prior Art
Surgical clip appliers are known in the art and have increased in popularity among surgeons by offering an alternative to conventional suturing of body tissues and vessels. Typical instruments are disclosed in U.S. Pat. No. 5,030,226 to Green et al. and U.S. Pat. No. 5,431,668 to Burbank, III et al. These instruments generally provide a plurality of clips which are stored in the instrument and which are fed sequentially to the jaw mechanism at the distal end of the instrument upon opening and closing of the handles at the proximal end of the instrument. As the handles are closed, the jaws close to deform a clip positioned between the jaw members, and as the jaws are opened to release the deformed clip, a new clip is fed from the series to a position between the jaws. This process is repeated until all the clips in the series of clips have been used.
In addition, many of the prior art instruments provide complex mechanical arrangements for closing the jaws while simultaneously preparing for feeding the next clip into the jaws after the clip positioned between the jaws is deformed and then released. These complex mechanisms, such as that shown in U.S. Pat. No. 5,431,668 to Burbank, III et al., require numerous parts which increases the cost of manufacture, as well as increasing the time it takes to assemble each instrument. These arrangements typically require additional moving parts, also tending to increase the cost of manufacture and increase the time of assembly.
Furthermore, many prior art instruments provide a clip feed mechanism in which the clip feed bar, or clip pusher bar is spring biased into a "load" position, and then is released and driven with considerable force and speed to drive a clip into the jaw mechanism. The forward movement of the clip is often arrested by either a clip stop mechanism at the jaws, by friction within the jaws, or by a combination of friction and the abrupt termination of the feed stroke of the pusher bar itself. A disadvantage of mechanisms of this type is that due to the force of the feed stroke, many times the clip itself may be inaccurately placed in the jaws, or may actually be overfed to the jaws, resulting in the clip becoming dislodged prior to application, or being otherwise inaccurately placed during application.
A need therefore exists for an instrument which controls the clip feeding procedure from the clip carrier to the jaws, so that the disadvantages of the prior art are overcome in that the possibility of misfeeding the clips to the jaws is substantially reduced or effectively eliminated. A need also exists for an instrument having a clip feed mechanism which reduces the force of the clip feed mechanism during the feed stroke to accurately place the clip into the jaws without misaligning the clip with respect to the jaws.